“It seemed that the nearby and mysterious planet was resorting to tricks to hide the secrets kept beneath its cover of clouds. As the probe drew nearer, Venus’ gravitational field increased its speed. The Doppler effect altered the wavelength of the signals received on Earth. The radio operators needed to be particularly vigilant so that the information sent from the station consistently landed in the narrow “throat” of the ground-based receivers.” Boris Chertok

During 1965 through January 1966, several significant Soviet unmanned scientific missions were launched. Five of the missions will be covered in this episode. We will begin with the Soviet Luna program.

The Zond program was one of two lunar exploration programs conducted by the Soviet Union to investigate the Moon and its vicinity. The program began in 1964 and ended in 1979. The early Zond’s 1-3 were originally designed for planetary exploration, while the latter Zonds (4-8) were sent on circum lunar flights. Additionally, the latter Zond vehicles were of a totally different in design. They were in fact automated versions of the manned Soyuz spacecraft…